A mantra is a word or phrase that is spoken or chanted over and over again, either mentally or aloud. They can be hard to translate, but it is not absolutely necessary to understand exactly what they mean.
Word Games: Mantras are words of power. Their effectiveness lies in the vibration of the sound. When they are vibrated correctly the sound strikes a certain frequency, which resonates within the subtle body, stimulating the psychic energy centers and releasing blockages in the energy flow.
The best known mantra is "Om." This is said to be the primal sound, the sound which, going forth at the beginning of time, brought the whole universe into being. Om is a "seed mantra," one from which other mantras are formed. A much-loved mantra is "Om mani padme hum." Approximately translated, this means "hail to the jewel in the lotus," the jewel being the divine spirit and enlightenment hidden within the lotus of our being.
Make Your Own Mantra: In the East, mantras are chosen for a pupil by a teacher. However, you can choose your own. This can be very simple. A single word such as "love" or "harmony" will suffice, or a phrase such as "peace to the world." You can use the name of a spiritual master or even your own name.
There are also plenty of ancient mantras springing from various spiritual traditions. If you have a specific religious belief, then try using part of a prayer, hymn, or saying as a mantra.